A. Field of the Invention
This invention relates to the field of art of gas measurement and analysis systems and particularly with respect to gas chromatograph systems.
B. Prior Art
Prior system have been used to achieve an estimation of the rate of change of a noise-burdened signal particularly in the field of instrumentation electronics and radar signal processing. Such signals are characterized by having amplitudes which are of the same order as the noise. Many forms of differentiator networks associated with operational amplifiers exist each of which suffers in varying degrees from problems of extreme sensitivity, "hang-up" in the saturation mode and other undesirable nonlinear modes of operation in the presence of noise. Other prior systems have used filtering networks. However, filters have been limited because of size and weight. In addition, filters have provided undesirable varying amounts of amplitude and phase distortion of the original signal when the frequency content of the signal being processed is in the approximate spectral range of the noise being eliminated.
Additional prior art exists in the area of "off-line" processing techniques in which data points are collected which contain the processed signal imbedded in a noise component. Digital processing methods are used to separate the signal from the noise component by employing analytical methods such as the "least squares" technique. By means of such techniques, the primary trend of the desired function can be determined. However, such methods are normally limited by the excessive degree of computation time required and the necessity of operating in non-real time. Many operational systems require real time computational capability due to memory size limitations and limited processing power (in terms of time) of miniprocessor and microprocessor systems.